AU2020269760B2 - Negative pressure wound dressing - Google Patents

Abstract

The invention relates to a multi-layer wound dressing for applying negative pressure to a wound. The dressing comprises a bioresorbable layer, for placement in contact with the wound; a fluid impermeable occlusive outer layer; a fluid porous porting layer positioned between the outer layer and the bioresorbable layer; and a fluid conduit in fluid communication with the porting layer, for coupling to a source of negative pressure. The porting layer comprises a multiplicity of fluid pathways between the conduit and the bioresorbable layer to allow for fluid transfer through the layers of the dressing to and from the bioresorbable. The bioresorbable layer comprises a plurality of apertures to enable exudate to flow from the wound to the porting layer.

Description

WO wo 2020/226511 PCT/NZ2020/050044

NEGATIVE PRESSURE WOUND DRESSING FIELD OF THE INVENTION

This invention relates to a wound dressing, in particular a dressing for the application of

negative pressure and/or the instillation of treatment fluids to a wound.

BACKGROUND The technique of applying negative pressure to augment the healing of soft tissues has been

utilised for many years with the core principle of the therapy remaining largely unchanged.

In the context of treating open wounds, negative pressure wound therapy (NPWT) typically

involves the placement of porous materials such as an open-cell foam, reticulated foam or

gauze onto the wound site, sealing the wound cavity with an occlusive layer and applying a

negative pressure to the sealed wound environment (see Figures 1 and 2). The clinical efficacy

of this treatment is well supported in areas such as for acute and chronic wounds, which have

demonstrated accelerated formation of granulation tissue in open wounds in response to the

treatment.

While the open architecture of the porous wound contacting layer allows for the effective

application of pressure to the wound and removal of wound exudate, a shortcoming with present NPWT dressing constructs is the susceptibility for healing granulation tissue to grow

in to the porous wound contacting layer. This results in trauma to the newly formed tissue

when the foam layer is removed. To prevent or minimise tissue in-growth it is necessary to

regularly change the dressing which requires additional time and expense. Furthermore, the

repeated dressing changes can induce acute trauma to the periwound or intact skin area around the wound further compounding the overall treatment time.

Collagen scaffolds, extracellular matrices and tissue graft materials provide another helpful

means to promote tissue growth and the regeneration of tissue in wounds. These

bioresorbable collagen-based materials contain biophysical and biochemical elements which

support the regenerating tissue through the various stages of healing. The collagen material

properties within these scaffolds can vary greatly which is largely attributed to the varying

xenogeneic or allogeneic origins and differing processing methods used during manufacture.

Collagen is a resorbable structural protein with a high affinity for water and so collagen

scaffolds can draw water into the fine pores of the material. Therefore, the use of these

materials is primary limited to the treatment of wounds with low levels of wound exudate.

The retained fluid within the scaffold can prevent cellular migration and proliferation which

can inhibit effective incorporation into the wound. In the context of NPWT, these materials

present a substantial barrier to the passage of negative pressure to the wound interface, with

the associated pressure drop rendering the NPWT treatment ineffective.

It It is is an an object of at object of atleast leastpreferred preferred embodiments embodiments of the of the present present inventioninvention to addressto address one of one of the abovementioned abovementioned disadvantages and/or to at to at least provide the public with a with usefula useful 27 Jan 2025 2020269760 27 Jan 2025

the disadvantages and/or least provide the public alternative. alternative.

In this In this specification specificationwhere where reference reference has made has been beentomade patenttospecifications, patent specifications, other other external external 5 documents, 5 documents, or other or other sources sources of information, of information, this isthis is generally generally to provide to provide a context a context for for discussingfeatures discussing featuresof of thethe invention. invention. Unless Unless specifically specifically stated stated otherwise, otherwise, referencereference to such to such external external documents documents ororsources sources ofof information information isisnot nottotobebeconstrued construed as as an an admission admission thatthat such documents such documents or such or such sources sources of information, of information, in any jurisdiction, in any jurisdiction, are priorare artprior artpart or form or form part of the the common generalknowledge knowledge in in thethe art. 2020269760

of common general art.

10 SUMMARY 10 SUMMARY OFOF THEINVENTION THE INVENTION

In In aa first first aspect, theinvention aspect, the invention broadly broadly consists consists in a in a wound wound dressingdressing for applying for applying negative negative

pressure to a pressure to a wound, thedressing wound, the dressingcomprising: comprising:a abioresorbable bioresorbablegraft graftlayer, layer, for for placement in placement in contact with the contact with the wound; wound;a aliquid liquid impermeable impermeable occlusive occlusive outer outer layer;a afluid layer; fluidporous porousporting porting layer positionedbetween layer positioned betweenthe the outer outer layerlayer andbioresorbable and the the bioresorbable graftand graft layer; layer; andconduit a fluid a fluid conduit 15 15 in in fluidcommunication fluid communication with with thethe porting porting layer, layer, forcoupling for couplingtotoaasource sourceofof negative negativepressure; pressure; whereinthe wherein the porting porting layer layer defines defines a multiplicity a multiplicity of fluid of fluid pathways pathways between between the and the conduit conduit the and the bioresorbable graft bioresorbable graft layer; layer; andand wherein wherein the bioresorbable the bioresorbable graft graft layer layer comprises comprises a plurality aofplurality of

apertures or slits apertures or slits to to enable enable fluid fluidflow flowfrom from the the wound to the wound to theporting portinglayer. layer. Each Eachaperture aperture comprises oneorormore comprises one moreslots slotsor orslits slits that that define defineone one or or more flaps, each more flaps, each flap flapbeing being movable movable 20 fromfrom 20 a closed a closed position position in which in which substantially substantially all flap all of the of the is flap is in contact in contact with thewith thetowound, wound, an to an openposition open positiontoto thereby thereby increase increase the size the size ofrespective of the the respective aperture. aperture.

The bioresorbable The bioresorbable layer layer may maycomprise comprise a pluralityofofmechanically a plurality mechanicallyinterlocked interlockedbioresorbable bioresorbable sheets.The sheets. The bioresorbable bioresorbable layer layer mayahave may have firstasheet first having sheet having a plurality a plurality of lugs of andlugs and a second a second sheet having sheet having aaplurality plurality of of apertures, apertures, each each lug lug of of the the first first sheet being located sheet being located through througha a 25 respective 25 respective aperture aperture in the in the second second sheet tosheet to interlock interlock the first the first sheet sheet with with the the second second sheet. sheet.

In In an an embodiment, thebioresorbable embodiment, the bioresorbable sheets sheets comprise comprise extracellularmatrix extracellular matrix(ECM). (ECM). TheThe ECM ECM may comprisereticulum. may comprise reticulum.

In an In embodiment, an embodiment, thebioresorbable the bioresorbable layercomprises layer comprises a plurality of a plurality of apertures, apertures, the the apertures apertures definingfluid defining fluid pathways. pathways.

30 In In 30 an an embodiment, embodiment, the apertures the apertures comprise comprise two intersecting two intersecting slotsslots to form to form a cross a cross shape shape and and to define to define one one or or more moreflaps flapsininthe thebioresorbable bioresorbablelayer, layer,wherein whereinthethe flaps flaps are are movable movable to to increase thesize increase the sizeofofthe theopening opening provided provided by aperture. by each each aperture. The The slots mayslots may be substantially be substantially X- X- shaped, Y-shaped, shaped, Y-shaped,C-shaped, C-shaped,U-shaped, U-shaped, or or V-shaped. V-shaped.

In In an an embodiment, theapertures embodiment, the aperturesare areformed formed through through thethe bioresorbable bioresorbable layer layer by by removing removing a a

35 slug 35 slug of of material material from from the the bioresorbable bioresorbable layer. layer.

2

In In an embodiment, an embodiment, thethe bioresorbable bioresorbable layer layer comprises comprises a plurality a plurality of of slitsdefining slits definingthe thefluid fluid pathways, each pathways, each slitslit defining defining one one or more or more flaps flaps in the in the bioresorbable bioresorbable layer,the layer, wherein wherein flaps the flaps 27 Jan 2025 2020269760 27 Jan 2025

are movable are movabletotoincrease increase thethe size size of of thethe opening opening provided provided by slit. by the the slit. The The slitsslits may may be be substantially substantiallyX-shaped, X-shaped, Y-shaped, C-shaped,U-shaped, Y-shaped, C-shaped, U-shaped,ororV-shaped. V-shaped.

55 In In an an embodiment, embodiment, the slits the slits or or slotsare slots aredie diecut cutfrom fromthe thebioresorbable bioresorbablelayer. layer.

Theslits The slits or or slots slots preferably preferablydefine define flaps flaps that that allow allow the the aperture aperture to open to open under pressure. under pressure.

In In an an embodiment, theporting embodiment, the portinglayer layer is is compliant and porous. compliant and porous. For Forexample, example,the theporting portinglater later may comprisea afluid-permeable fluid-permeablefoam foam such as as PVAPVA (Polyvinyl alcohol)foam. foam. 2020269760

may comprise such (Polyvinyl alcohol)

In In an an embodiment, wherein embodiment, wherein anan upper upper surface surface of of the the portinglayer porting layeris is undulating. undulating.

10 10 TheThe porting porting layer layer maymay comprise comprise an antimicrobial an antimicrobial treatment. treatment.

In In an an embodiment, thedressing embodiment, the dressingfurther furthercomprises comprisesa apressure pressure distributionlayer distribution layer between betweenthe the porting porting layer layer and and the the occlusive occlusive layer. layer.The Thepressure pressure distribution distributionlayer may layer maycomprise comprise an an open open cell cell foam oraathree-dimensional foam or three-dimensional fabric. fabric.

In an embodiment, In an embodiment, the pressure the pressure distribution distribution layer comprises layer comprises a plurality a plurality of fluid of fluid flow flow channels channels

15 15 that that areare substantiallyperpendicular substantially perpendiculartotothe the interface interface between the foam between the foamlayer layerand andthe thepressure pressure distribution layerto distribution layer toallow allowfluid fluidtotoflow flowthrough throughthethe pressure pressure distribution distribution layer.layer.

In an embodiment, In an embodiment, thethe conduit conduit comprises comprises a distal a distal end end portion portion having having an opening an opening in fluid in fluid communicationwith communication withthe theporting portinglayer. layer.

In an embodiment, In an embodiment, the conduit the conduit distaldistal end portion end portion is substantially is substantially arch-shaped. arch-shaped.

20 In In 20 some some forms, forms, the conduit the conduit comprises comprises a duala lumen dual lumen conduitconduit comprising comprising a strut apositioned strut positioned along along aa central central axis axis of of one oneofofthe thelumens lumens to to prevent prevent the the conduit conduit from from collapsing collapsing underunder compression. compression.

Optionally, theconduit Optionally, the conduit comprises comprises a lumen a lumen which which is is elliptical elliptical in shape. in shape.

In In an an embodiment, theconduit embodiment, the conduitis is aa dual dual lumen conduit comprising lumen conduit comprisingaa primary primaryconduit conduitto to apply apply 25 25 a negative a negative pressure pressure to dressing to the the dressing and aand a secondary secondary conduitconduit for introducing for introducing fluid fluid to theto the dressingororfor dressing forfacilitating facilitating pressure pressure measurement. measurement.

In an In an embodiment, thedressing embodiment, the dressingfurther furthercomprises comprisesa asleeve sleevecomprising comprisinga a portfor port forreceiving receiving aa portion of the portion of theconduit conduit therein therein in in a secure a secure arrangement arrangement to the to attach attach theto conduit conduit to the dressing. the dressing.

The sleeve The sleeve may maycomprise compriseanan elastomeric elastomeric material. material.

30 30 In In some some embodiments, embodiments, the sleeve the sleeve formsforms a divider a divider between between a negative a negative pressure pressure receiving receiving areaarea of the of the dressing dressing and and an an ambient pressurearea. ambient pressure area.

In In an an embodiment, theocclusive embodiment, the occlusivelayer layercomprises comprisesa asubstantially substantiallytransparent transparentregion regionand andthe the porting porting layer layer comprises oneorormore comprises one more viewing viewing apertures apertures beneath beneath the the transparent transparent region region to to enable visualinspection enable visual inspectionof of at at least least a portion a portion of the of the bioresorbable bioresorbable layer.layer. 3

In In an embodiment, an embodiment, the the occlusivelayer occlusive layercomprises comprises a polyurethane a polyurethane sheet sheet having having an adhesive an adhesive surface. surface. 27 Jan 2025 2020269760 27 Jan 2025

In In an an embodiment, thewound embodiment, the wound dressing dressing comprises comprises a mouldable a mouldable adhesive adhesive sealseal for for surrounding surrounding a wound, a wound, wherein wherein the the seal seal comprises comprises butyl rubber, butyl rubber, a and a filler, filler, and a tackifying a tackifying resin. Preferably, resin. Preferably,

55 the the sealseal is removable is removable and re-sealable and re-sealable against against a patient’s a patient's skin. In skin. In some some forms, the forms, seal is the non-seal is non- curing. curing. In In some embodiments, some embodiments, thethe seal seal is is removable removable from from a skin a skin surface surface by stretching by stretching the the adhered seal. adhered seal.

Described herein is Described herein is aa mouldable andremovable mouldable and removable adhesive adhesive seal seal forfor surrounding surrounding a wound, a wound, the the 2020269760

seal comprising seal comprising butyl butyl rubber, rubber, a filler, a filler, andand a tackifying a tackifying resin. resin.

10 10 In In an an embodiment, embodiment, the seal the seal is repositionable is repositionable andand deformable. deformable.

In In an an embodiment, theseal embodiment, the sealis is non-curing. non-curing.

In In an an embodiment, theseal embodiment, the sealis is removable removablefrom froma askin skinsurface surface by by elongating elongating the the adhered adheredseal. seal.

Also described Also described herein hereinisisananadhesive adhesive seal seal application application system system comprising comprising the mouldable the mouldable adhesive seal described adhesive seal describedininrelation relation to to the thesecond second aspect, aspect, andand further further comprising comprising a first a first 15 15 removable removable release release sheet sheet adhered adhered to side to one one side of adhesive of the the adhesive seal,seal, and and a second a second removable removable release release sheet sheet adhered to aa second adhered to secondside side of of the the adhesive adhesive seal, seal, wherein wherein the the second secondremovable removable release sheetisisstretchable. release sheet stretchable.

In an embodiment, In an embodiment,thethe second second removable removable release release sheet sheet comprises comprises silicone. silicone. Optionally, Optionally, a a removable protectorsheet removable protector sheetadhered adheredtotothe thesecond secondremovable removable release release sheet. sheet.

20 20 In In some some forms, forms, the the first first removable removable release release sheet sheet is paper is paper based based and and comprises comprises an adhesive an adhesive contacting sidecoated contacting side coated in in silicone. silicone.

In some In some forms, forms, thethe adhesive adhesive seal seal is is elongate elongate and stretchable. and stretchable.

Optionally, theseal Optionally, the sealisisnon-curing. non-curing.

In In a a second aspect, the second aspect, the invention invention broadly consists in broadly consists in aa wound treatmentsystem wound treatment system comprising comprising 25 25 a wound a wound dressing dressing as described as described above above in relation in relation to to the the first aspect, first aspect, and and a a mouldable adhesive mouldable adhesive seal for surrounding seal for a wound, surrounding a wound, the seal the seal comprising comprising butyl rubber, butyl rubber, a and a filler, filler, and a tackifying a tackifying resin resin wherein the wherein the mouldable mouldable adhesive adhesive seal seal is is appliedaround applied around thethe perimeter perimeter of the of the wound wound to the to the patient’s patient'sskin. skin. The The seal sealmay may comprise oneor comprise one or more moreofofthe thefeatures features described described above. above.

In In an an embodiment, theocclusive embodiment, the occlusivelayer layer is is adhered over the adhered over the mouldable mouldableadhesive adhesiveseal. seal.

30 30 In In an an embodiment, embodiment, a negative a negative pressure pressure source source is coupled is coupled to conduit to the the conduit to apply to apply a negative a negative

pressure to the pressure to the wound. wound.

In In an an embodiment, thesystem embodiment, the system comprises comprises a reservoirfor a reservoir forcollecting collecting exudate exudate removed fromthe removed from the dressing. dressing.

4

WO wo 2020/226511 PCT/NZ2020/050044 PCT/NZ2020/050044

This invention may also be said broadly to consist in the parts, elements and features referred

to or indicated in the specification of the application, individually or collectively, and any or

all combinations of any two or more said parts, elements or features. Where specific integers

are mentioned herein which have known equivalents in the art to which this invention relates,

such known equivalents are deemed to be incorporated herein as if individually described.

The term 'comprising' as used in this specification and claims means 'consisting at least in

part of'. When interpreting statements in this specification and claims that include the term

'comprising', other features besides those prefaced by this term can also be present. Related

terms such as 'comprise' and 'comprised' are to be interpreted in a similar manner.

It is intended that reference to a range of numbers disclosed herein (for example, 1 to 10)

also incorporates reference to all rational numbers within that range and any range of rational

numbers within that range (for example, 1 to 6, 1.5 to 5.5 and 3.1 to 10). Therefore, all sub-

ranges of all ranges expressly disclosed herein are hereby expressly disclosed.

As used herein the term '(s)' following a noun means the plural and/or singular form of that

noun. As used herein the term 'and/or' means 'and' or 'or', or where the context allows, both.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described by way of example only and with reference to

the accompanying drawings.

Figure 1 is a perspective view of a prior art negative pressure wound dressing.

Figure 2 is a perspective view of a further prior art negative pressure wound dressing.

Figure 3 is a cut-away perspective view of a first embodiment negative pressure wound dressing described herein.

Figure 4 is an exploded perspective view of the wound dressing of Figure 3.

Figure 5 is a cut-away perspective view of a second embodiment negative pressure wound dressing. 25 dressing.

Figures 6(i) and 6(ii) are perspective views of the porting layer of Figure 5, where Figure 6(i)

shows the upper surface of the layer, and Figure 6(ii) shows the underside.

Figures 7(i) to 7(iii) are detail views showing a cut away portion of the porting layer of Figure

5, where Figure 7(i) is an isometric view showing the upper surface of the layer, Figure (ii) 7(ii)

is an overhead perspective view, and Figure 7(iii) is an underside perspective view.

Figures 8(i) and 8(ii) are perspective views of an alternative embodiment porting layer having

undulating ribs, where Figure 8(i) shows the upper surface of the layer, and Figure 8(ii) shows

the underside.

WO wo 2020/226511 PCT/NZ2020/050044 PCT/NZ2020/050044 Figures 9(i) to 9(iii) are detail views showing a cut away portion of the porting layer of Figures

8(i) and 8(ii), where Figure 9(i) is an isometric view showing the upper surface of the layer,

Figure 9(ii) is an overhead perspective view, and Figure 9(iii) is an underside perspective

view. view.

Figures 10(i) and 10(ii) are perspective views of an alternative embodiment porting layer

having square ribs, where Figure 10(i) shows the upper surface of the layer, and Figure 8(ii)

shows the underside.

Figures 11(i) to 11(iii) are detail views showing a cut away portion of the porting layer of

Figures 10(i) and 10(ii), where Figure 11(i) is an isometric view showing the upper surface of

the layer, Figure 11(ii) is an overhead perspective view, and Figure 1 (iii) is 1(iii) is an an underside underside

perspective view.

Figures 12(i) to 12(iv) are a series of schematics showing the block build' process of regenerating tissue forming in passages of the porting layer and the atraumatic removal

following successful treatment Figure 13 is a cut-away perspective view showing a portion of

an exemplary multi-sheet lugged bioresorbable layer according to one embodiment.

Figures 14(i) and 14(ii) are partial section views of exemplary multi-sheet lugged bioresorbable layers, where Figure 14(i) shows an embodiment having lugs formed from the

top sheet engaging the underlying sheets, and Figure 14(ii) shows an embodiment additionally having a bottom lugged sheet engaging the overlying sheets.

Figures 15(i) and 15(ii) illustrate an embodiment of the bioresorbable layer having X-shaped

apertures, where Figure 15(i) shows the layer flat, and Figure 15(ii) shows the edges of the

apertures deforming to allow more flow through the apertures.

Figures 16(i) to 16(iii) further illustrate the operation of the bioresorbable layer apertures of

Figures 15(i) and 15(ii), where Figure 16(i) is a plan view of an aperture on a flat sheet,

Figure 16(ii) illustrates the aperture deforming when the sheet is placed on a contoured wound

surface, and Figure 16(iii) shows the edges of the apertures deformed to allow more flow

through the aperture.

Figures 17(i) to 17(iii) illustrate fluid flow paths through the bioresorbable layer of Figures

16(i) to 16(iii), where Figure 17(i) is a cut-away perspective view illustrating the sheet placed

on a contoured wound surface; Figure 17(ii) is a schematic side view showing the edges of

the apertures deformed to allow more flow through the aperture, and Figure 17(iii) illustrates

fluid flow paths through the apertures.

Figure 18 illustrates a prior art graft with staggered linear expansion fenestrations, where

Figure 18(i) is a cut-away perspective view illustrating the graft placed on a contoured wound

surface; Figure 18(ii) illustrates deformation of the fenestrations to accommodate wound

surface undulations, and Figure 18(iii) illustrates the restricted flow through the graft.

WO wo 2020/226511 PCT/NZ2020/050044

Figures 19(i) to 19(iv) are perspective views illustrating four exemplary alternative

embodiment bioresorbable layers, where Figure 19(i) shows an embodiment having oval apertures, Figure 19(ii) shows an embodiment having X-shaped slits, Figure 19(iii) shows an

embodiment having Y-shaped slits, and Figure 19(iv) shows an embodiment having C-shaped

slits.

Figures 20(i) and 20(ii) are plan views illustrating two further exemplary alternative embodiment bioresorbable layers, where Figure 20(i) shows an embodiment having circular

apertures, and Figure 20(ii) shows an embodiment having C-shaped slots.

Figures 21(i) and 21(ii) illustrate the operation of the bioresorbable layer apertures of Figure

19(iv), where Figure 21(i) is a perspective view showing deformation of the bioresorbable

layer to conform to a contoured wound surface, and Figure 21 (ii) shows the flaps, defined by

the slits, deformed to allow more flow through the apertures.

Figures 22(i) and 22(ii) illustrate the operation of the bioresorbable layer apertures of Figure

19(iii), where Figure 22(i) is a perspective view showing deformation of the bioresorbable

layer to conform to a contoured wound surface, and Figure 22(ii) shows the flaps, defined by

the slits, deformed to allow more flow through the apertures.

Figures 23(i) and 23(ii) illustrate the operation of the bioresorbable layer apertures of Figure

19(i), where Figure 23(i) is a perspective view showing deformation of the bioresorbable layer

to conform to a contoured wound surface, and Figure 23(ii) shows flow through the apertures.

Figures 24(i) to 24(iii) illustrate an alternative form bioresorbable layer formed from

reticulum, where Figure 24(i) is a perspective view showing the textured top surface of a

reticulum sheet, Figure 24(ii) is a perspective view of the top of the layer, with X-shaped

slots, and Figure 24(iii) is a perspective view of the underside of the layer.

Figure 25 is an illustrative perspective view showing the wound dressing described herein

place over a foot wound.

Figure 26 is view corresponding to Figure 25, showing the process of removing the mouldable

strip of the dressing, from the foot.

Figure 27 is an illustrative perspective view showing placement of the wound dressing described herein on an arm wound.

Figure 28 is view corresponding to Figure 27 showing the process of removing the mouldable

strip of the dressing, from the arm.

Figure 29 is a cross-sectional schematic showing the mouldable rubber adhered to skin.

Figure 30 is a view corresponding to Figure 29 showing removal of the mouldable rubber.

PCT/NZ2020/050044

Figure 31 is a cut-away perspective view of a negative pressure wound dressing according to

a third embodiment, having a pressure distribution layer.

Figure 32 is an exploded perspective view of the wound dressing of Figure 31.

Figure 33 is a cut-away perspective view of a negative pressure wound dressing according to

a fourth embodiment, having an alternative embodiment pressure distribution layer.

Figure 34 is a cross-sectional view of an embodiment dual lumen conduit, comprising a primary conduit to apply a negative pressure to the dressing and a secondary conduit for

instilling fluid to the dressing or for pressure measurement.

Figure 35(i) and 35(ii) are illustrate views of an embodiment of a sleeve, where Figure 35(i)

relates to a view along the axis of the through-hole of the component, and Figure 35(ii) relates

to an isometric view of the sleeve.

Figure 36(i) and 36 (ii) are illustrative views of the embodiment dual lumen conduit of Figure

34 assembled to the elastomeric sleeve component of Figure 35 (i) & 35 (ii), where the dual

lumen conduit has been cut along the second end of the conduit to expose the primary and

secondary conduits of the dual lumen conduit along a length.

Figure 37 is a cut-away perspective view of a negative pressure wound dressing according to

a fifth embodiment, incorporating the assembled dual lumen conduit and elastomeric sleeve

component of Figure 36(i) and 36 (ii).

Figure 38 is an exploded perspective view of the wound dressing of Figure 37.

Figure 39 is an exploded perspective view of an apparatus used to prepare a bioresorbable

layer of the invention.

Figure 40 is an exploded perspective view of the tooling used within apparatus described in

Figure 39.

Figure 41 (i) and 41 (ii) are cross-sectional views illustrating the process of the operating the

apparatus in Figure 39 to prepare a bioresorbable layer of the invention.

Figure 42 is an exploded perspective view of the pressure drop measurement apparatus described herein.

Figure 43 is chart displaying the results from measuring the pressure drop across various

wound contacting devices in response to two different levels of applied negative pressure.

WO wo 2020/226511 PCT/NZ2020/050044

DETAILED DESCRIPTION

I. Definitions

The term "extracellular matrix" (ECM) as used herein refers to animal or human tissue that

has been decellularised and provides a matrix for structural integrity and a framework for

carrying other materials.

The term "decellularised" as used herein refers to the removal of cells and their related debris

from a portion of a tissue or organ, for example, from ECM.

The term "polymeric material" as used herein refers to large molecules or macromolecules

comprising many repeated subunits, and may be natural materials including, but not limited

to, polypeptides and proteins (e.g. collagen), polysaccharides (e.g. alginate) and other

biopolymers such as glycoproteins, or may be synthetic materials including, but not limited

to, polypropylene, polytetrafluoroethylene, polyglycolic acid, polylactic acid, and polyester.

The term "interlock" or "interlocking" as used herein refers to the mechanical engagement of

two or more overlapping sheets of material.

The term "sheet" as used herein refers to a substantially flat flexible section of ECM or

polymeric material.

The term "lug" as used herein refers to a section of a sheet that has been partially cut out so

that the lug remains fixedly attached to the sheet via a connection bridge.

In this specification and claims, the terms 'negative pressure' and 'vacuum pressure' may be

used interchangeable to mean a gauge pressure less than an ambient pressure and an absolute pressure less than atmospheric pressure. Alternative terms include `sub-atmospheric 'sub-atmospheric

pressure', 'suction pressure' or 'reduced pressure'. For example, a negative pressure or

vacuum pressure of 100mmHg is -100mmHg gauge pressure or around 660mmHg absolute

pressure. The terms 'higher', 'increase', when used in relation to negative or vacuum

pressure, are intended to mean higher or increasing negative pressure. For example, a gauge

pressure of -150mmHg (610mmHg absolute) is higher than a gauge pressure of -100mmHg (660mmHg absolute). Similarly, in relation to the terms 'lower', 'decrease', when used in

relation to negative or vacuum pressure, are intended to mean lower or decreasing negative

pressure. For example, a gauge pressure of -100mmHg is lower than a gauge pressure of -

150mmHg.

In this specification and claims, unless the context indicates otherwise, the term "exudate" 'exudate' is

intended to mean any fluid removed from a wound site of a patient. For example, exudate

may comprise fluid produced by the patient, and/or fluid applied to the wound site by the

system, including air or treatment fluid such as saline, or fluid providing medication, or fluid

WO wo 2020/226511 PCT/NZ2020/050044

from a surgical intervention that may have introduced or administered treatment fluids to the

wound site via a separate route such as by injection.

II. Device

Various embodiments will now be described with reference to Figures 1 to 40. In these

figures, like reference numbers are used in different embodiments to indicate like features,

with the addition of a multiple of 100. Directional terminology such as the terms 'front', 'rear',

'upper', 'lower', and other related terms are used in the following description for ease of

description and reference only, it is not intended to be limiting.

The invention generally provides a multi-layered wound dressing system that includes a

wound dressing comprising at least one layer of bioresorbable material and at least one other

layer of material comprising apertures that act as fluid ports to allow fluid to pass through

the layers to and from the wound site. The fluid may be a gas or liquid or both. The multi-

layer wound dressing also comprises an adhesive portion, such as a mouldable seal, that

surrounds the wound site to define the boundary of a wound treatment region. Typically, the

adhesive portion is provided on the intact skin outside the boundary of the wound. The adhesive portion additionally seals to a liquid impermeable occlusive layer to provide an

enclosed environment around the wound and define the wound treatment region. The multi-

layer wound dressing system also includes a negative pressure component that comprises at

least one conduit having a distal end that terminates within the enclosed environment creating

by the wound dressing and that allows treatment fluid to be delivered to the wound site and

exudate to be removed from the wound site. The conduit also allows for negative pressure to

be applied to the enclosed environment surrounding the wound. The negative pressure helps

assist healing of the wound and therefore can reduce the time taken for the wound to heal.

Figures 3 and 4 illustrate a first exemplary embodiment wound dressing 101 suitable for

applying negative pressure to a wound 103. The dressing 101 comprises a bioresorbable layer 105 for placing in contact with a wound surface 103, a liquid impermeable occlusive

outer layer 107, a porting layer 109 between the outer layer 107 and the bioresorbable layer

105, and a fluid conduit 111 in fluid communication with the porting layer 109, for coupling

to a source of negative pressure.

Bioresorbable layer

With reference to Figures 13 and 14, the wound contacting bioresorbable layer 105 comprises

a flexible multi-sheet structure. In the embodiments exemplified herein, the bioresorbable

layer 105 comprises a plurality of overlaid sheets 113a, 113b that are mechanically interlocked to each other, for example utilising portions of one or more of the sheets to engage

with one or more of the other sheets. Mechanically interlocking the sheets 113a, 113b secures

the sheets together without the need for the addition of other materials such as adhesives or

WO wo 2020/226511 PCT/NZ2020/050044 PCT/NZ2020/050044

sutures, or the need for treatments such as compression and dehydration. In addition, these

multi-sheet structures have a greater combined tensile strength than individual sheets.

The multi-layer structure of the bioresorbable layer 105 may be produced according to the

method described PCT application PCT/NZ2015/050215, which is incorporated herein by reference. Example multi-sheet interlocked bioresorbable layers 105, 105' produced according to this method are illustrated in Figures 13, 14(i), and 14(ii)). In the embodiments

shown, the bioresorbable layer 105 comprises a first, lugged sheet 113a, 113a having a plurality of lugs 115 formed by cutting a U-shaped or C-shaped slit in the first sheet to create

a tab-like 'lug'. The underlying or overlying sheets 113b have a plurality of perforations 117

and each lug 115 is pushed through the respective underlying or overlying perforations 117

to interlock the sheets together to create a lugged laminate. The resulting structure contains

recesses 114 in the lug sheet where each lug 115 was cut from the sheet. Each lug 115,

remains attached to its respective lug sheet 113, via a connection bridge 116, thereby interlocking the sheets to hold them together.

In the exemplary embodiments 105, 105' shown in Figures 14(i) and (ii), there are three or

four perforated sheets, but alternatively the bioresorbable layer may comprise more or fewer

perforated sheets. The number of sheets superimposed at and secured at different points of

the bioresorbable layer may vary, for example, if different properties are required at different

areas of the bioresorbable layer.

In some embodiments, the bioresorbable layer may comprise more than one lug sheet 113a,

for example, having both upper and lower lugged sheets as illustrated in Figure 14(ii). In that

embodiment, three perforated sheets 113b' are sandwiched between a top lug sheet and a bottom lug sheet 113a'. Lugs 115' from the top lug sheet have been pushed through the perforations 117' of the middle sheets 113b' to the underside of the lower lug sheet, and lugs

115' from the lower lug sheet have been pushed through the perforations of the middle sheets

113b' to the top surface of the top lug sheet.

The lugs of the lower lug sheet may be aligned with the lugs in the top sheet as shown in the

embodiment of Figure 14(ii), or they may be offset to prevent lugs on different lug sheets

being pushed through the same perforations 117'. The mechanical properties of the product

can be further tailored to the application needs by modifying the shape of the lugs, or utilising

a different lugging pattern, size, density and/or shape.

The lugs 115, 115' may or may not be pushed through all of the underlying or overlying

sheets and, for embodiments with more than one lug sheet, may or may not be pushed through the other lug sheet.

The perforations 117, 117' for the lugs in the multi-sheet lugged bioresorbable layer provide

a plurality of micro-channels through the sheet. These channels advantageously assist with

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fluid flow from the wound through the bioresorbable layer and assist with pressure application

to the wound due to the channels provided by the perforations for the lugs.

The bioresorbable layer sheets 113 comprise extracellular matrix (ECM) or a polymeric material. ECM-derived matrices for use in embodiments of the present invention are collagen-

based biodegradable matrices comprising highly conserved collagens, glycoproteins,

proteoglycans and glycosaminoglycans in their natural configuration and natural concentration. One extracellular collagenous matrix for use in this invention is ECM of a warm-

blooded vertebrate. ECM can be obtained from various sources, for example, gastrointestinal

tissue harvested from animals raised for meat production, including pigs, cattle and sheep or

other warm blooded vertebrates. Vertebrate ECM is a plentiful by-product of commercial meat

production operations and is thus a low cost tissue graft material. One exemplary method of

preparing ECM is described in United States Patent No. 8,415,159.

In some embodiments of the invention, resorbable polymeric material may be included in the

bioresorbable layer as either lug sheets, pierced sheets, and/or in another three-dimensional

form. For example, meshes comprising synthetic materials such as polyglycolic acid, polylactic acid and poliglecaprone-25 are will provide additional strength in the short-term,

but will resorb in the long term. Alternatively, the polymeric material may be a natural

material, or derived from a natural material, such as proteins (e.g. collagen), polysaccharides

(e.g. alginate), glycoproteins or other materials.

In some embodiments, the bioresorbable layer 105 may comprise one or more sheets of reticulum 1113 (see Figure 24) which may be produced according to the method described in

PCT application PCT/NZ2009/000152, which is incorporated herein by reference. Reticulum

is a propria-submucosa of the forestomach of a ruminant that possesses a unique raised 'honeycomb' appearance on the luminal surface of the tissue. These honeycomb features are

created by a series of continuous native ridges comprised of predominately dense collagen

which create an undulating and varied textured surface on the luminal face of the reticulum

tissue. The abluminal surface is generally smooth in appearance following the delamination

and removal of the muscle layer. While these raised ridges retain an element of elasticity,

they are relatively incompressible when subjected to the negative pressure applied within

wound therapy.

The raised ridges of the reticulum also assist with the distribution of pressure across the

surface of each individual honeycomb pocket by preventing the collapse and sealing of the

adjacent dressing materials, which is a unique feature of the native material. The bioresorbable layer 105 may additionally be treated for the delivery of bioactive materials to

the wound site. The bioactive materials may be endogenous to the ECM used in the preparation of a graft product or may be materials that are incorporated into the ECM and/or

polymeric material layers during or after manufacturing. Bioactive materials delivered to the

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wound site in this way are known to be beneficial for promoting cellular function, including

wound healing and other desirable physiological and pharmacological functions.

In other embodiments, the bioresorbable layer 105 may comprise one or more sheets of ECM

sourced from the rumen, which is another propria-submucosa of the forestomach of a

ruminant and is also described within PCT application PCT/NZ2009/000152.

With reference to Figures 13, 14 and 24 (i) to 24 (iii) the use of forestomach tissue in the

construction of a lugged multi-sheet bioresorbable layer 105 carries other additional benefits.

As described within PCT application PCT/NZ2009/000152, tissue scaffolds sourced from

forestomach tissue typically have a contoured luminal surface of varying appearance

according to the particular origin of the scaffold (such as the rumen, reticulum or omasum)

where the abluminal surface is generally smooth in appearance following the delamination

and removal of the muscle layer. With particular reference to the rumen, the luminal surface

of this tissue scaffold is populated with a number of surface protrusions known as papillae,

which visually appear as small 'hair-like' features that project from the luminal surface. When

a bioresorbable layer 105 is constructed according to the aforementioned lugged laminate

process using rumen tissue, the resultant lugged laminate comprises an interstitial space

formed in-between adjacent sheets of the laminate as a result of the papillae located within

each interstitial space that prevent the adjacent sheets from forming a tight seal between the

layers. This interstitial space is not limited to only laminates using rumen tissue. Other

embodiments that comprise resorbable foams and other resorbable polymeric materials may

also comprise an interstitial space between adjacent sheet layers.

The multi-sheet bioresorbable layer 105 comprises a plurality of primary apertures, which

may comprise slits (formed from cuts made without removing material from the layer), slots

(having spaced apart side edges as a result of removed material from the layer) or any other

suitable form of opening such a regular or irregularly shaped opening, through the bioresorbable layer 105 to define a multiplicity of fluid pathways. These pathways enable

fluid flow from the wound to the porting layer 109.

In one embodiment shown in Figures 15(i) to 17(iii), the apertures in the bioresorbable layer

105 comprise an array of x-shaped apertures formed by two intersecting slots 119. The

bioresorbable layer is flexible, such that each X-shaped aperture may define four generally

triangular flaps 121 in the bioresorbable layer. The two free edges of each triangular flap 121

are formed by a pair of slots that extend across the same generally central point in a perpendicular arrangement to each other to form a cross, with the third edge of the triangular

flap forming a hinge with the body of the bioresorbable layer.

These x-shaped slots allow the bioresorbable layer 105 to flex to conform to undulations in a

wound surface 103, as illustrated in Figure 17(i), with the edges of a given slot able to move

closer together to accommodate a concavity, or able to spread apart to accommodate a

WO wo 2020/226511 PCT/NZ2020/050044 convex surface. Therefore, the bioresorbable layer is able to be substantially in full contact

with the wound surface. The x-shaped apertures also provide other benefits by allowing the

passage of wound exudate fluid through the layer and also allow the supplied negative pressure therapy to the wound surface 103 over a large equivalent area without removing a

large area of material, thereby reducing the amount of bioactive material being delivered to

the wound by the bioresorbable layer 105.

In another embodiment shown in Figure 16(i) the x-shape formed by the intersecting slots

119 has a width and height of approximately 5.5 mm. The slot preferably has a width of approximately 0.5 mm, with approximately 5 mm² of resultant bioresorbable material

removed from the layer 105. In contrast to this, if the apertures formed in the bioresorbable

later are in the form of a circular perforation similar to that of Figure 20 (i) with a diameter

of approximately 5.5 mm then approximately 24 mm² of bioresorbable material must be removed to provide an aperture of this size and a comparable level of supplied negative

pressure to the wound surface and capacity of fluid exchange through the bioresorbable layer

105 as that experienced using the cross shaped apertures of Figure 16(i).

In other embodiments, the width and height of the x-shaped aperture may be longer in one

direction than the other or may comprise a variety of different sized slots across the bioresorbable layer 105. The length of the slots forming the x-shape may range from about

3 mm to about 15 mm in width and length, with the width of each slot ranging from about

0.2 mm up to about 2 mm in width.

In some forms, apertures are provided in the bioresorbable layer in a generally regular

arrangement, such as by being located in substantially aligned columns and rows. In other

forms, the apertures may be arranged in an offset or staggered arrangement. In yet other

forms, the apertures may be provided in an irregular arrangement or a random arrangement

on the bioresorbable layer.

Figures 18(i) to 18(iii) show a known graft product which includes linear fenestrations/slits

419 rather than apertures formed as a result of material being removed from the product. If

used in a dressing, these fenestrations/slits are less able to take up the undulations in both

the longitudinal and transverse directions. The linear slits only provide a narrow opening for

the fluid flow 420 through the graft as they are formed without removing material from the

graft product. Consequently, the linear slits are only capable of allowing removal of fluid from

a smaller region of the wound site than the apertures of the present invention. In addition,

the linear fenestrations 419 close easily once the graft 405 is in situ, due to moisture taken

up by the graft 405 causing swelling of the graft near the slits 419, which further closes the

narrow openings. Regenerating tissue, wound fluids such as blood, red blood cells, fibrin and

other wound phenomena, such as slough and healing tissue debris, also collect and populate

in these narrow fenestrations and can cause the fenestrations to block. Furthermore, the

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lateral movement of the graft within the wound can cause the linear slit fenestrations to close

with the slightest movement, preventing any fluid exchange through the layer.

In contrast, as illustrated in Figures 15(ii), 16(iii), 17(ii) and 17 (iii), the flaps 121 defined by

the X-shaped apertures/slots of the dressing of the present invention are able to move

upwards to increase the size of the opening and thereby to increase the size of the fluid

pathways 120 provided by the slots 119. This may happen under pressure, for example due

to the negative pressure being applied to the dressing, and allows fluid paths to be maintained

even if there is some swelling of the material surrounding the slots. As well as facilitating the

removal of fluid from the wound site, maintaining the fluid pathways allows a more efficient

application of negative pressure to the wound site because larger openings in the bioresorbable layer are advantageously associated with less pressure drop over the thickness

of the bioresorbable layer 105. Additionally, the X-shaped slots are also less prone to closing

when the graft moves within the wound as the X-shaped openings skew in response to lateral

movement to maintain the openings through the bioresorbable layer.

In alternative embodiments, the bioresorbable layer primary apertures 119 may have alternative shapes. For example, rather than being X-shaped, the apertures may be slots of

another two dimensional shape such that they each define one or more flaps that is movable

to accommodate contours and is movable to increase the size of the fluid pathway through

the aperture. For example, suitable slot shapes include slots having a curved portion or

comprising two or more linear portions arranged in an angle to form an arrowhead type

arrangement. Each flap is created by two or more adjacent linear slots edges, or by a convex/curved slot, with the slot edge or edges defining the free (moving) edges of the flap

and a virtual line between two distal ends of the curved slot or pair of slots forming the hinge

of the flap. In some forms, rather than being X-shaped, in alternative embodiments the slots

119 may be Y-shaped, C-shaped, U-shaped, or V-shaped. Each Y-shaped slot defines three flaps, each C-shaped, U-shaped, or V-shaped slot defines one flap.

Each slot or other primary aperture is formed by removing material from the bioresorbable

layer. For example, by blanking, by making spaced apart cuts and removing the intervening

material, or by die cutting or laser cutting whereby material is removed by a single pass of

the laser beam, the slot width corresponding to the laser beam width.

Alternatively, rather than a slot where material has been removed from the bioresorbable

layer, the flaps for the fluid passages may be formed using shaped slits, created by cut lines

where no material is removed from the sheet. The slits may be linear or of a curved shape

as described above in relation to the slots, having a two-dimensional shape, or the slots may

be formed by a non-linear cut or from interesting/irregular shaped cuts, such that each slit

defines one or more flaps that is movable to accommodate contours of the wound site. The

flaps are movable to 'open' to create a fluid pathway or increase the size of the fluid pathway

PCT/NZ2020/050044

through the layer at the slit. Figures 19(ii) to 19(iv) illustrate some exemplary slit arrangements. Figure 19(ii) illustrates an embodiment 605 having X-shaped slits 619, with

each slit 619 defining four flaps that are movable in the manner described above in relation

to the X-shaped slots. Figures 19(iii), 22(i), and 22(ii) illustrate an embodiment 705 with Y-

shaped slits 719, each slit being formed from three intersecting linear cuts to define three

flaps 721. Figures 19(iv), 21(i), and 21(ii) illustrate an embodiment 805 with variously

oriented C-shaped slits 819, with each slit 819 defining a single flap 821.

As a further alternative, the primary apertures in the bioresorbable layer may comprise a

plurality of openings that don't form flaps, for example round apertures 919 as shown in

Figure 20(i), oval or oblong apertures 519 as shown in Figures 19(i), 23(i), and 23(ii), or

other shaped apertures. In these embodiments, the bioresorbable layers do not comprise movable flaps to increase the size of the fluid pathway through the layer. Instead, the

apertures provide a larger opening than the slots described above, for the efficient transfer

of pressure to the wound and passage of fluid. However, this increase in the opening size is

associated with a reduction of the area of the bioresorbable layer 505, 905 that is in contact

with the wound surface, thereby reducing the therapy area. Sheets having larger apertures

may also be more difficult to handle.

In some embodiments, to provide a lugged multi-layered dressing with apertures 119 within

the bioresorbable layer 105 that do not interfere with the interlocking lugs, the apertures may

be arranged in a grid pattern and the lugs 115 may be arranged between at least some of

the adjacent apertures in a layer. The width of the apertures 119 may also be longer in one

axis than the other to provide sufficient space on the layer for the interlocking lugs 115, such

that the width of each primary aperture 119 may span the equivalent length of two or several

adjacent lugs 115 but be limited in height. In other embodiments the apertures 119 within

the bioresorbable layer 105 may be arranged in a staggered pattern.

Porting layer

The porting layer 109 is positioned on top of the bioresorbable layer 105, between the bioresorbable layer and the occlusive layer 107. The porting layer 109 defines a multiplicity

of fluid pathways between the conduit 111 and the bioresorbable layer 105, to enable the

porting of pressure to the bioresorbable layer and for the passage of wound exudate out of

the bioresorbable layer 105.

The porting layer 109 maintains spacing between the bioresorbable layer 105 and the occlusive outer layer 107 under the application of negative pressure to the dressing via the

conduit 111. This porting layer 109 also provides some protection to the wound 103 by

cushioning the wound, and assists to distribute the negative pressure from the conduit 111

to the bioresorbable layer across a wide area, rather than to the area immediately adjacent

the conduit.

PCT/NZ2020/050044

The porting layer 109 comprises a material selected to minimise the pressure drop across the

layer 109 while also discouraging tissue-in growth. The porting layer 109 material must also

provide sufficient structural integrity to allow for the passage of fluid through the porting layer

under elevated levels of pressure, such as between approximately 125 mmHg to approximately 250 mmHg of vacuum pressure. In one embodiment, the porting layer comprises a compliant porous material such as a solid-state, water permeable synthetic foam.

The foam is of at least a semi-open cell nature to allow fluid passage through the foam layer.

The greater the porosity of the foam layer and the stiffer the material, the less the pressure

drop.

In an embodiment, the porting layer 109 comprises an antimicrobial open cell foam or a semi-

open/semi-closed cell foam such as a PVA foam. The foam is flexible and compressible to

conform to and cushion the wound site 103. Some openness is required in the sub-layer 123

to allow the porting of pressure and the transfer of liquid through the layer. However, more

open foams such as reticulated polyurethane are generally more susceptible to tissue in-

growth, which is undesirable. Utilising a semi-closed foam such as PVA foam immediately

adjacent to the bioresorbable layer reduces the ability for tissue to grow into the foam layer.

Additionally, the porting layer 109 may also comprise a series of channels 125 to further

improve the porting of pressure and the transfer of liquid through the porting layer 109.

With reference to the embodiment shown in Figure 37 and Figure 38, the porting layer 1409

comprises 20 comprises a hydrophilic, a hydrophilic, non-reticulated non-reticulated polyurethane polyurethane foam foam that that comprises comprises an an absorbent absorbent polymer, such as sodium polyacrylate, within the foam sub layer 1423 to provide a hydrophilic

property. The hydrophilic non-reticulated polyurethane foam is a medium density foam with

a pore size of approximately 200 um µm to approximately 400 um. In other embodiments, the foam contains a distribution of pore sizes ranging from approximately 10 um µm to approximately

600 um. µm. In some forms, the foam may be a dense foam with a pore size of approximately 20

um µm to approximately 50 um, µm, and may contain a distribution of pore sizes ranging from approximately 5 um µm to approximately 150 um. µm.

The surface of the porting layer 1409 may comprise a layer of silicone that interfaces with the

bioresorbable layer 1405. In the embodiment of Figures 37 and 38, the porting layer 1409

comprises a staggered pattern of x-shaped channels 1425 that are comparable to the shape

illustrated in Figure 16 (i). The channels 1425 are approximately 12 mm in height and

approximately 12 mm in width with a slot width of approximately 2 mm when presented to the wound site. The height and width of the channels 1425 may vary from approximately 3

mm to approximately 15 mm and may also vary in width from 0.5 mm to 8 mm. The channels

1425 are spaced in staggered pattern with repeating channels 1425 spaced approximately 20

mm apart along a first axis and approximately 10 mm apart on a second axis which is perpendicular to the first axis. The porting layer 1409 is approximately 8 mm thick, but may

otherwise be from approximately 3 mm thick to approximately 30 mm thickness depending

PCT/NZ2020/050044

on the wound 103 geometry, such as depth, and comfort requirements of the site, such as

areas around the lower spine and buttocks.

In another embodiment the porting layer 1409 may comprise a medium density PVA foam with a distribution of pore sizes ranging from approximately 10 um µm to approximately 600 um.

The foam may also be a dense foam with a distribution of pore sizes of approximately 20 um µm

to approximately 30 um. The PVA foam may also retain an antimicrobial agent. The porting

layer 1409 may also contain a series of x-shaped channels 1425 arranged in a staggered

pattern. The channels 1425 are approximately 6 mm in height and approximately 6 mm in width with a slot width of approximately 1.5 mm when measured in a non-hydrated or dry

format. 10 format. TheThe height height andand width width of of thethe channels channels 1425 1425 maymay vary vary from from approximately approximately 3 mm 3 mm to to

approximately 15 mm and may also vary in width from approximately 0.5 mm to approximately 8 mm. The channels 1425 are spaced in staggered pattern with repeating channels 1425 spaced approximately 14 mm apart along a first axis and approximately 7 mm

apart on a second axis which is perpendicular to the first axis. The porting layer 1409 is

approximately 5 mm in thickness when measured in a dry format but may also be from

approximately 2 mm thick to 20 mm thickness depending on the wound 103 geometry, or may be abutted together to treat areas such as deep tunnelling wounds or areas where there

is undermining.

The porting layer 109 has wicking properties to wick liquid away from the bioresorbable layer.

PVA foams, unlike reticulated foams, are denser as they contain a higher amount of PVA material in the cell walls of the foam pores which allow high levels of moisture to be absorbed

and retained within the foam. When utilised for the porting layer 109, the PVA provides a

gradient of fluid absorbance which draws excess moisture away from the bioresorbable layer

to allow cells important to wound healing to migrate into the bioresorbable layer and

proliferate. PVA foams that are combined with antimicrobial agents also additionally reduce

the infection risks associated with retained wound fluid sitting on a wound while they can also

elute the antimicrobial agent to manage high bioburden levels and unwanted microbial activity. Examples of such antimicrobials can include silver, tetracyclines, gentium violet,

methylene blue and chlorhexidine.

In addition to the multiplicity of fluid pathways inherent in the foam, provided for by the

porosity of the foam, the porting layer 109 may comprise an array of through channels 125

that are substantially perpendicular to the interface between the porting layer 109 and the

bioresorbable layer 105 and extend through the full thickness of the porting layer 109. These

channels 125 reduce the pressure drop across the porting layer 109 to ensure negative

pressure is effectively applied to the bioresorbable layer 105.

The through channels 125 are preferably linear and x-shaped, as shown in Figure 37, but may

otherwise be of any suitable cross-section and configuration, such as round or oval as shown

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in the alternative embodiment of Figure 5. The cross-section of the through channels is

preferably many times larger than that of the fluid passages inherent in the foam.

The through channels 124, together with the semi-closed nature of the foam, ensure that a

low pressure drop is provided across the porting layer 109 to allow the effective application

of negative pressure, but while reducing tissue in-growth. Figure 12 illustrates the process

of tissue growing into a through channel 124 of the porting layer as the wound heals. However, because ingrowth of the tissue into the foam itself is minimal, the porting layer can

be lifted from the wound without also removing significant amounts of tissue, as shown in

Figure 12(iv).

In the embodiment of Figure 3, an upper surface of the porting layer 109 is undulating with

peaks 127 and valleys 128. The occlusive layer 107 is stretched across the porting layer 109,

sitting on the peaks 27 such that at the valleys 28, a gap is formed between the occlusive

layer and the adjacent top surface of the porting layer 109. Referring to Figure 7 (i), these

gaps form fluid flow paths 124 to assist the application of negative pressure across the whole

width of the porting layer 109, and also to assist the passage of fluids from the porting layer

109 to the conduit 111.

Referring to Figures 6(i) to 7(iii), in the embodiment of Figure 3, the upper surface of the

porting layer 109 is undulating in two directions with an array of peaks 127 defining a lattice

of diagonally intersecting flow paths 124. The openings of the through channels 124 are

situated in the valleys 128 between the peaks 127 such that they are in fluid communication

with the fluid flow paths passing between the peaks 127.

In alternative embodiments, the upper surface of the porting layer 109 may comprise a series

of ribs 327. The ribs 327 may be curved as shown in Figure 8(i) to 9(iii), or they may be

stepped, as shown in the example of Figures 10(i) to 11(iii). In the embodiment of Figure

10(i), the openings of the fluid channels 324 span the peaks of the ribs 327. This allows the

free flow of fluids along the adjacent valleys 328, thereby ensuring that the supplied negative

pressure is evenly distributed across the porting layer 109. The distributed pressure is then

ported via the channels 324 to the underside 323 of the porting layer, to evenly distribute

pressure across the adjacent bioresorbable layer.

The porting layer may be either partially or completed adhered to the bioresorbable layer or

may have a non-adhesive surface. Additionally, the lug features of the bioresorbable layer

could be inserted into the foam to mechanically lug the two components together.

Fluid conduit

The fluid conduit 111 comprises a flexible tube, for example a plastic or elastomeric walled

tube. The tube may have a wall thickness sufficient to avoid the walls collapsing under the

applied negative pressure, for example, 50-250mmHg, or up to 650mmHg. Suitable conduits

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utilised for wound therapy purposes will be apparent to those skilled in the art. Alternatively,

the conduit 111 may comprise a thin wall supported by a bracing truss or other material or

structure to prevent the walls of the tube collapsing under negative pressure. For example,

the conduit 111 may comprise a tube comprising a membrane or thin wall surrounding a resilient coil or an open cell foam or three dimensional fabric or matrix.

A first end of the conduit 111 is configured for attachment to a source of negative pressure

such as a pump (not shown) or other common negative pressure wound therapy system. For

example, the conduit 111 may have an end coupling such as a luer connector or threaded connector for attaching to a negative pressure source. Alternatively, the conduit 111 may be

sized to receive or to be received by a suitable connector as would be apparent to a skilled

person.

A second end 112 of the conduit 111 is in fluid communication with the porting layer 109 and

arranged to apply pressure to the porting layer 109. In the embodiment shown in Figures 3

& 4, the second end 112 of the conduit is positioned between the occlusive layer 107 and the

porting layer 109. A distal end of the conduit 111 extends into an opening formed between

the occlusive layer 107 and the patient. In some forms, the distal end of the conduit 111

may be secured to the patient's skin to reduce the risk of the second/distal end of the conduit

being inadvertently pulled from the dressing 101. For example, the distal end of the conduit

111 may be secured using a piece of adhesive tape 131 placed over the conduit 111 and

adhered to the skin. In the embodiment shown, the tape is positioned between the edge of

the pressure distribution layer 106 and the adjacent edge of the occlusive layer 107 and

covered by the occlusive layer 107.

Figures 35 (i) and 35 (ii) illustrate one form of sleeve 132 that comprises a passage 137 for

receiving a portion of the conduit 111. The sleeve 132 forms a separator that defines a

negative pressure region on one side of the sleeve and an ambient pressure region on the

other side of the sleeve 132. A hermetic seal can be formed between the exterior surface of

the conduit 111 and the interior surface of the passage 137, such as by fastening the conduit

111 to the sleeve 132 by bonding, welding or adhering the conduit to the sleeve. The The underside, or skin contacting side, of the sleeve may comprise an adhesive layer 136 such as

a medical grade acrylic based pressure-sensitive adhesive, a silicone gel adhesive or other

suitable adhesive material to assist with locating and securing the conduit and sleeve to the

skin. In some forms, the sleeve comprises an elastomeric material to provide an element of

flex and grip.

Alternatively, the occlusive layer 107 may comprise an opening and the second/distal end

112 of the conduit 111 may terminate at the upper surface of the occlusive layer 107 SO so as

to apply negative pressure across the underside of occlusive layer and those layers beneath

the occlusive layer, in a similar manner to the arrangement of the dressing shown in Figure

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2. Alternatively, the distal end of the conduit 111 may extend through an aperture in the

occlusive layer 107 to apply negative pressure across the layers of the wound dressing beneath the occlusive layer. In some embodiments, the occlusive layer is sealed to the distal

end of the conduit to prevent fluid leaks.

The conduit 111 may comprise a dual lumen conduit having a primary lumen 133 to supply

negative pressure to the dressing and one or more secondary lumens 134. The secondary lumens 134 may be utilised for introducing fluid to the wound site or to enable measurement

and monitoring of the pressure within the dressing. Alternative embodiments may instead

comprise a plurality of conduits to introduce fluids to the wound site and to monitor pressure

across the site.

In the embodiment shown in Figure 34, the conduit 111 comprises a primary lumen 133 and

a smaller secondary lumen 134 arranged side-by-side. The primary lumen 133 has an elliptical

profile with a major axis length of approximately 4.5 mm and minor axis length of approximately 3.8 mm, while the secondary lumen 134 has a circular profile of approximately

1.5 mm in diameter. The open area of the primary lumen 133 is approximately 10 mm² while

the open area of secondary lumen is approximately 2 mm². The elliptical profile of this

embodiment coupled with the side-by-side arrangement is intended to ensure that the conduit

111 lays generally flat against the various contours of the body in situations where the source

of negative pressure is located remotely from the wound, such a situation being likely when

the wound is located on the upper arm or lower leg regions of the body.

The dual lumen conduit 111 in this embodiment is preferably made from a medical grade thermoplastic elastomer, with a 'soft feel', preferably of a Durometer Hardness of between

Shore 30 A and Shore 80 A, to ensure comfort against the skin and wound when pressure is

applied to the dressing 101 during use, such as when a patient may be lying on the dressing

101 for long durations.

It is also important that the surface texture of the conduit material has a low coefficient of

friction to prevent unwanted bioburden and particulate accumulating on the surface of the

conduit, such is the issue with polysiloxane (silicone) materials. However, the conduit could

be made from any other readily available elastomeric material such as thermoplastic

polyurethane, synthetic rubber, silicone or other plasticized synthetic polymers.

The embodiment in Figure 34 also incorporates an angled strut 135 along the minor axis of

the primary lumen 133 to prevent the collapse of the tube when pressure is applied to the

top of the conduit 111 or dressing 101, such as when the patient may be lying on top of

device. This strut 135 provides the conduit with a soft and conforming profile to reduce the

risk that the conduit may create pressure related injuries to the patient after prolonged

localised compression between the patient's body and the conduit, particularly where the

conduit is in contact with the spine, hip, ankle, knee or shoulder.

21

The second/distal end 112 of the conduit or a portion of the conduit adjacent the second end

112 may have an enlarged open area for receiving fluid into the conduit 111 and for better

distributing the pressure from the conduit 111 across the porting layer. For example, the

conduit may be provided with an elongate elliptical opening, such as by providing a tapered

distal end 112. In some forms, the taper of the distal end 112 may be so gradual as to allow

the distal end of the conduit to sit almost flat against an upper surface of one of the layers of

the wound dressing, such as the occlusive layer 107. This enlarged open area of the distal

end reduces the likelihood of the conduit becoming blocked at the distal end 112 and also

aids in the distribution of negative pressure across the surface of the porting layer. In

alternative embodiments, the conduit may comprise a series of teeth within the internal lumen

of the conduit, so that if a portion of the wall of the conduit is cut away to provide a tapered

distal end 112, the teeth are exposed and prevent collapse of the remaining portion of the

tube wall under compression. This may also reduce the point loading of the conduit onto the

wound, which is a limitation of the existing prior art (Figure 2), and which can cause the

conduit port to be pressed into the wound causing pain.

With reference to the alternative embodiment shown in Figures 34, 36 (i) and 36 (ii), the

conduit 111 comprises a dual lumen conduit where the elongate opening at the distal end 112

has been formed by removing a length 'L' of the conduit extending from an area near the

elastomen elastomer sleeve 132 to the terminal end point of the distal end 112 of the conduit. In effect,

the distal end portion 'L' of the dual lumen conduit is open along the lower side to expose

each of the lumens to the upper surface of the dressing layer below. This arrangement is

preferably oriented to preserve the strut 135 of the dual lumen conduit, to help prevent

collapse of the remaining portion of the conduit, and to expose the secondary lumen 134

along the same length 'L'. The exposed interior surface of the distal end portion 'L' is intended

to be supplied in a sufficient length to extend substantially across the longest axis of the

wound and to facilitate the distribution of negative pressure across the uppermost surface of

the porting layer. Provided that the dual lumen conduit is sufficiently flexible, the conduit 111

may be positioned in any shape or pattern across the top of the porting layer to ensure

adequate distribution of the supplied negative pressure.

In the embodiment shown in Figure 3 and 4, the distal end portion of the conduit, adjacent

the second/distal end 112, is substantially arch-shaped, with the underside of the arch open

to the top of the porting layer 109. In this embodiment, the length of the arched end portion

of the conduit is about 30% of the width of the dressing, but in alternative embodiment, the

length of the end portion may be between about 20% and about 90% of the width of the

dressing 101.

In an alternative embodiment, the second/distal end 112 may split into a plurality of branches

that each extend in different directions across the top surface of the porting layer 109 to

assist in distributing pressure and receiving fluid into the conduit 111 from across the full area

WO wo 2020/226511 PCT/NZ2020/050044

of the porting layer 109. Each of these branches may be of a similar internal diameter to the

main conduit 111, or smaller, and may comprise an arched portion with an underside in fluid

communication with the porting layer 109.

Pressure distribution layer

Optionally, the dressing may comprise an additional layer between the porting layer and the

occlusive layer. Figures 31 to 33 show such alternative embodiment dressings 1201, 1301.

The additional layer is a pressure distribution layer 1206 for distributing pressure applied by

the conduit 1211 substantially across the full surface of the underlying porting layer 1209,

1309. The pressure distribution layer 1206, 1306 sits directly on the porting layer 1209, 1309,

between the porting layer and the occlusive layer 1207, 1307.

The pressure distribution layer 1206, 1306 is flexible and compressible to conform to and

cushion the wound site. The pressure distribution layer 1206, 1306 has an open form defining

a multiplicity of fluid pathways between the conduit 111 and the porting layer 1209, 1309, to

minimise the pressure drop across the thickness of the pressure distribution layer 1206, 1306.

As examples, the pressure distribution layer 1206, 1306 may comprise an open cell foam, or

a three-dimensional fabric, such as spacer fabric. The openness of the pressure distribution

layer 106 is higher than the openness of the material of the porting layer 1209, 1309, the

openness at least partly offsetting the pressure drop from using a more closed material such

as silicone foam for the porting layer.

In the embodiments shown, the pressure distribution layer 1206, 1306 comprises a three

dimensional woven polyethylene fabric. The woven layer has an open form that defines a lattice of pressure distribution channels between the threads forming the fabric. The multi-

directional flow paths ensure fluid can always flow through much of the layer even if some

pathways become blocked.

Optionally, the pressure distribution layer 1206 may comprise an array of interconnected

pressure distribution channels 1208 that are substantially perpendicular to the interface

between the porting layer 1209, 1309 and the pressure distribution layer 1206, 1306. Fluid

can flow along these vertical channels but also sideways between the channels, that is,

between the threads forming the fabric. In alternative embodiments, the pressure distribution

layer may comprise an open cell foam, for example reticulated foam.

Occlusive layer

The occlusive layer 107 is substantially liquid impermeable and substantially air impermeable.

Preferably, the occlusive layer 107 has a high water vapour transmission rate (WVTR), also

known as Moisture Vapour Transmission Rate (MVTR), to provide a sealed environment for

the application of negative pressure but to allow moisture to exchange through the dressing.

This helps to prevent maceration of the intact peri-wound and also allows excess fluids and

23

PCT/NZ2020/050044

exudate to vent out of the wound environment. An underside of the occlusive layer 107 optionally comprises an adhesive surface for removably adhering a peripheral portion of the

dressing 101 to a patient's skin to seal the wound cavity and thereby allow control of the

pressure within the cavity.

The surface area of the occlusive layer 107 is preferably larger than that of the underlying

bioresorbable and porting layers 105, 109, with the peripheral portion of the occlusive layer

107 optionally forming an adhesion flap 108 for adhering to the peri-wound 104 to secure the

dressing in place. In some embodiments, the adhesive coating may only be applied to the

underside (patient contacting side) of this adhesion flap 108.

The adhesive surface of the occlusive layer may be created by applying an adhesive coating

to all or to a peripheral portion of the underside (patient contacting side) of the occlusive

layer 107. Where the adhesive coating is applied to all of the underside of the occlusive

layer, the occlusive layer 107 may optionally be adhered to the porting layer 1091.

In another forms, an adhesive or seal may be separately applied around the periphery of the

occlusive layer or a sealing layer may be placed over the occlusive layer SO so S to extend beyond

the periphery of the occlusive layer to adhere and seal the wound dressing to the patient's

skin. skin.

The occlusive layer 107 may be substantially transparent or may comprise a transparent region to enable monitoring of the underlying layers. In one embodiment, the porting layer

109 comprises one or more viewing apertures that are located beneath the transparent region

to enable visual inspection of at least a portion of the bioresorbable layer. This may assist

with monitoring the progress of the wound healing.

In the embodiment shown, the occlusive layer 107 is a transparent thin polyurethane based

sheet (for example, about 15-60 um µm thick, preferably about 20 um µm thick to provide good

MVTR while still being easy to handle), and having a skin friendly 20-80 um µm thick layer of

silicone adhesive applied to the underside. Alternative adhesives include modified rubber

based adhesives and pressure sensitive acrylic adhesives, or a combination thereof.

Mouldable seal

To improve the liquid tightness of the seal between the dressing and the patient's skin surface,

and to protect the peri-wound area 104, a mouldable seal/adhesive 129 may be placed around

the wound perimeter, but preferably within the boundary of the occlusive layer 107. The

occlusive layer 107 is typically placed over the mouldable seal/adhesive 129 and adheres to

the skin around the outside of the area defined by the mouldable strip 129. In other forms,

the mouldable seal may be placed over and around the periphery of the occlusive layer 107

to seal against both the occlusive layer and the patient's skin.

WO wo 2020/226511 PCT/NZ2020/050044 PCT/NZ2020/050044

The mouldable seal/adhesive may comprise a non-curing mouldable material. Typically, the

mouldable seal comprises a homogenous material in which the adhesive strength is generally

consistent throughout the material. This allows the material to be stretched, deformed,

kneaded and manipulated to create any shape whilst maintaining a high level of adhesive

strength. Consequently, the mouldable seal/adhesive may be repositionable, deformable and

stretchable.

In the embodiments shown, the mouldable seal comprises a butyl-rubber based adhesive

component. The component comprises synthetically sourced butyl-rubber which has been mixed with a tackifying resin agent, an organic filler to deaden the rubber compound into a

soft form tacky singular form, and optionally a stabilising agent. In the preferred embodiment,

the compound consists of Polyisobutylene, an aliphatic hydrocarbon resin as a tackifying

agent, calcium carbonate as a filler material and Poly(dicyclopentadiene-co-p-cresol) as a

stabilising agent. Alternatively, any suitable hypoallergenic tackifying resin could be used

during the mixing and extrusion process of making the seal material, while other filler

materials could include talc, dolomite, barytes, kaolin and silica. In alternative embodiments,

the mouldable seal may comprise alternative mouldable adhesives or alternative rubber

sources, such as mouldable polysiloxane (silicone), styrene butadiene, polychloroprene (neoprene), nitrile rubber or compounds that include blends of the aforementioned synthetic

rubbers.

The mouldable seal/adhesive 129 offers several other advantages such as high levels of skin

adhesion with a low level of trauma or pain during removal. The adhesive properties of the

mouldable seal can be adjusted by varying the amount of tackifier added during the mixing

and extrusion process, which can be adjusted to achieve comparable adhesion properties to

the acrylic based pressure sensitive adhesives typically used for medical dressings and devices

to achieve high skin adhesion. Unlike coated adhesive dressings, the mouldable seal/adhesive

129 can be stretched off the skin after use so as to break adhesion between the adhesive

surface of the seal and the skin. The mouldable seal/adhesive 129 is also removable and

repositionable on the skin while retaining a high level of adhesive strength.

A further advantage of the mouldable seal/adhesive 129 is the ability to directly apply release

agents comprising either isopropyl alcohol (IPA), hexamethyldisiloxane, 1,1,1,2-

tetrafluoretan, ISOPARAFFIN L, (2-methoxymethylethoxy) propanol, Hydrotreated heavy naphtha (petroleum) or a blend of agents to the mouldable seal/adhesive 129 as required

during the removal of the dressing.

Other advantages of the mouldable seal/adhesive 129 include its thickness and softness which

allows the material of the seal to be depressed and moulded into skin folds and crevices that

are common on patients and which can lead to leaks and subsequent loss of negative pressure

to the wound, as shown in Figure 29, if an ineffective seal is formed between the dressing

WO wo 2020/226511 PCT/NZ2020/050044 PCT/NZ2020/050044

and skin. The softness of the mouldable seal/adhesive can also be adjusted by changing the

rubber material used during the mixing and extrusion process. The amount of filler added

during manufacture can increase or decrease the softness of the mouldable seal/adhesive.

The mouldable seal 129 may be provided in a strip form. In some forms, the seal is provided

in a strip comprising a width of approximately 10 mm, a thickness of approximately 3 mm

and a length of approximately 250 mm. In some forms, the seal strip may otherwise be

provided in any widths ranging from approximately 5 mm to approximately 30 mm and with a thicknesses ranging from approximately 2 mm to approximately 8 mm, and a length ranging

from approximately 50 mm to approximately 400 mm. In some forms, the mouldable seal

129 may be provided in a roll with a total length ranging from approximately 200 mm to approximately 5000 mm. In some forms, the seal may be manually formed to a desired shape

from a block of mouldable material, such as by shaping the material into an elongate, long

sausage-shaped strip.

In some forms, an elongate, flat strip of the mouldable material is provided on a first

removable release sheet, which is adhered to one side of the mouldable strip 129. A second

removable release sheet is adhered to the opposite second side of the mouldable strip, such

that the mouldable strip is sandwiched between the releasable sheets. In other forms the

mouldable adhesive 129 is provided in a roll with release sheets attached to both sides of the

overlapping overlappingsurfaces of the surfaces roll. of the roll.

The first removable release sheet may be a paper-based material or any other suitable material, such as a plastic material, that is attached to a first surface of the mouldable strip,

i.e. the patient-contacting side of the mouldable strip. This first removable release sheet

protects the mouldable strip during storage and handling and is removable to expose a first

surface of the mouldable seal strip. The surface of the paper-based material contacting the

mouldable strip may be coated with a release coating, such as silicone or any other release

agents such as Polytetrafluoroethylene (PTFE), to reduce the adhesion between the first

removable release sheet and the mouldable strip for easy removal of the first release sheet.

The second removable release sheet adheres to a second surface of the mouldable strip opposite the first surface. This second removable release sheet protects the mouldable strip

during placement of the strip around the wound. The second removable release sheet is preferably a thin flexible sheet of silicone or any other suitable material that is able to stretch

along with the mouldable strip 129 to allow the mouldable strip to be manipulated and shaped

as required to conform to the peri-wound site, without removal of the second release sheet.

The surface of the second release sheet contacting the mouldable strip may be coated with a

release coating to reduce the adhesion between the second removable sheet and the mouldable strip for easy removal of the second release sheet.

WO wo 2020/226511 PCT/NZ2020/050044

The second release sheet is preferably transparent or semi-transparent such that the skin

surface the mouldable strip is being applied to is visible to the clinician during application in

order to assist with the application. For example, the second removable release sheet may

comprise a silicone sheet.

The second removable release sheet is removed from the mouldable strip after the mouldable

strip is applied to the patient, thereby removing the need for a medical professional to touch

the surface of the mouldable strip to apply it.

A removable protector sheet is adhered to the second removable release sheet to protect the

second removable release sheet during transport. This protector sheet may be a paper-based

material or may be of any other suitable material, such as a plastic material that is removable

to expose the second release sheet.

Application and removal of the dressing

The dressings 101, 201, 401 described above and other embodiments thereof are intended for use in the treatment of chronic wounds, for example diabetic ulcers and burns. Figures

25 and 26 illustrate the dressing 101 applied to a foot wound and an arm wound respectively.

To To apply apply the the dressing, dressing, the the mouldable mouldable material material is is first first applied applied around around the the peri-wound peri-wound as as

described above. The mouldable material is pressed into the skin 104 surrounding the wound,

thereby filling in skin undulations and creases as illustrated in Figure 29, to act as a skin

barrier and reduce fluid leakage from the dressing.

The bioresorbable layer 105 is then fitted over the wound surface in full contact with the

surface and following the wound contours. The porting layer 109 is then placed over the

bioresorbable layer, the conduit 111 is secured in place over the porting layer 109, and the

arrangement is then covered by the occlusive layer and sealed to ensure the wound is air-

tight.

The first end of the conduit 111 is coupled to a source of negative pressure such as a vacuum

pump, and the pump operated to create a continuous or intermittent vacuum within the sealed

dressing. The negative pressure assists the removal of fluid from the wound and may improve

circulation to improve wound healing.

To remove the dressing, the occlusive layer 107 is peeled off the skin, and the conduit 111

and porting layer 109 are removed. The vacuum pump may comprise a reservoir for collecting

exudate liquids removed from the dressing.

Referring to Figures 26, 28, and 30, in a final step, the mouldable seal 129 can be removed

from the patient's skin by stretching the mouldable seal in a longitudinal direction as

illustrated. As the seal is elongated, it gently releases from the patient's skin 104 minimising

the likelihood of damage to the skin.

WO wo 2020/226511 PCT/NZ2020/050044

The bioresorbable layer does not need to be removed from the wound, as it breaks down

naturally with time.

EXAMPLES Example 1: Method of Manufacture

A bioresorbable layer 105 with x-shaped apertures 119 was prepared according the following

method. With reference to Figures 39 - 41, a sheet of reticulum tissue was prepared according

to the method described within PCT application PCT/NZ2009/000152 to provide a material 95

for processing using a blanking/perforating apparatus 89.

The blanking apparatus 89 includes an upper press assembly that comprises a punch retainer

plate 92, a punch pin assembly 99 and a clamping plate 90. The punch pin assembly 99 includes a punch 93 that is shaped to produce the desired final aperture, and a punch pin

retainer 91.

In this example, the punch 93 is shaped to produce the x-shaped aperture 119 shown in Figure 16 (i) and has a width and height of approximately 5.5 mm with a slot thickness or

width of approximately 0.5 mm.

The blanking apparatus 89 includes a presser plate 94, which is aligned to traverse along the

same axis as the upper press assembly, defined by the punch retainer plate 92, punch pin

assembly 99 and a clamping plate 90, and the lower die plate 97, which is retained by a die

nest 98.

The punch retainer plate 92, presser plate 94 and lower die plate 97 are aligned with high

precision to ensure a tight clearance fit with the punch 93 when it travels through the presser

plate 94 and lower die plate 97 during the blanking/perforating process.

With reference to Figure 41(i), the material for blanking 95 is placed on the lower die plate

97 and the pressure plate 94 and upper press assembly is contracted to advance the punch

93. The presser plate 94 engages with the material 95 to firmly hold the sheet in place while

the upper press assembly continues to advance.

Figure 41(ii) illustrates the punch 93 passing through the material 95 to blank/punch out a

slug 96 of material, thereby forming the aperture 119 in the material 95. In other words, the

apertures are formed in the layer of bioresorbable material, by removing a slug from the layer

of material. The material 95 is then indexed, or moved in a transverse direction, to repeat

the process until the required number of apertures 119 are formed in the material.

Example 2: Measuring pressure drop across various bioresorbable layers

The following example outlines the apparatus and test method used to assess and compare

the pressure drop across various materials and different forms of bioresorbable layers. With

WO wo 2020/226511 PCT/NZ2020/050044

reference to Figure 42, a pressure drop test apparatus 79 was constructed that comprises a

base plate 81, base support 80 and clamping ring 86. The clamping ring 86 includes a peripheral groove (not shown in Figure 42) to house a rubber o-ring or other form of seal 85.

The base plate 81 includes two ports 82 that are each connected to a separate pressure sensor. Each pressure sensor is capable of accurately measuring vacuum pressure across a

range of 0 - 400 mmHg. The pressure sensors are referred to herein as measurement points

P2 and P3. The two ports 82 are spaced approximately 45 mm apart. The base plate 81 may

also include three spare ports 83 that are spaced approximately 45 mm away from a central

pressure measuring port 82.

A test specimen 84 was cut to fit within a central recess on the base plate 81 and was subsequently secured in place by fastening the clamping ring 86 to the base plate 81 using

the fastening components located around the periphery of the clamping ring 86 and the base

plate 81.

Prior to proceeding further, the specimen was rehydrated within the test apparatus according

to the manufacturer's instructions and excess fluid was removed from the apparatus. For the

materials that relate to the described invention, test specimens were rehydrated using physiological saline for approximately 5 minutes and any excess fluid was removed from the

apparatus prior to testing.

All testing was performed by placing a 100 mm X 100 mm sized piece of reticulated open-cell

polyurethane foam 87 (V.A.C. R GRANUFOAM R - K.C.I / Acelity R) in the central opening of the clamping ring 86, which was sized to ensure a leak-free and consistent fit with the

foam. Each test was then performed with an adhesive polyurethane drape (V.A.C. R Drape -

K.C.I / Acelity R R)) and and centrally centrally placed placed portal portal 87 87 (SENSAT.R.A.C. (SENSAT.R.A.C. TM TM Pad Pad -- K.C.I K.C.I // Acelity Acelity R) R

affixed over the top of the setup.

A 'y-connector' was then fitted to the centrally placed portal to allow one end of the conduit

to be connected to a pressure sensor with the other end of the conduit to be connected to a

controlled source of negative pressure. The pressure sensor placed next to the drape is herein

referred to as measurement point P1. Prior to and following any testing the pressure sensors

at measurement points P1, P2 and P3 were verified to ensure the calibration was within

specification.

Each test was then performed according to the following sequence:

1. Pressurise measurement point P1 to the required pressure level.

2. Maintain pressure for 5 minutes to verify the system is free of any leaks.

3. Maintain the pressure set point for a further 5 minutes while logging the pressure from

measurement points P1, P2 & P3 at 1 second intervals.

4. Repeat the test cycle 3 or more times for the same test specimen to establish the

average pressure measurements at the 3 measurement points (P1, P2 & P3).

5. Assess the data to determine whether P1 was held constant within +5 ±5 mmHg throughout the 5 minute data acquisition period (step 3 above).

6. Remove the test specimen and perform two further replicate tests of the same test

specimen to determine the pressure drop of each material type.

The test was performed with four different materials where a 'Foam Only' test was performed

as a control. The four different materials were denoted as the following:

1. BI-LAYER CGAG - A bioengineered composite wound matrix that comprises Type-1

Bovine collagen that has been cross linked with glycosaminoglycan. This wound matrix

is affixed to a layer of silicone and been fenestrated using a series of staggered linear

cuts, similar to that of Figure 18.

2. CORC - A resorbable composite collagen dressing that comprises 45% oxidized regenerated cellulose (ORC) and 55% collagen.

3. 3-PLY LUGGED - A 3-ply multi-layer bioresorbable layer similar to that of Figure 14

(i), prepared according to the method described PCT application PCT/NZ2015/050215,

using lyophilized sheets of ovine forestomach matrix, or rumen sourced and processed

according to PCT application PCT/NZ2009/000152. 4. 3-Ply LUGGED with APERTURE - A 3-ply multi-layer bioresorbable layer, the same as

3 above, where the layer comprised x-shaped apertures prepared according to example 1 with an aperture geometry of 5 mm long X 5 mm wide with a slot thickness

or width of approximately 0.5 mm, where the apertures were positioned in a staggered

pattern with repeating apertures positioned 20 mm apart on a first axis and 10 mm

apart on apart ona asecond axis second thatthat axis lieslies perpendicular to the to perpendicular first theaxis. first axis.

The testing was performed at a vacuum pressure of 40 mmHg and 200 mmHg with the results

from the testing shown in Figure 43.

Claims (35)

CLAIMS CLAIMS 27 Jan 2025

1. A wound dressing for for applying negative pressure to atowound, a wound, the the dressing comprising: 2025 1. A wound dressing applying negative pressure dressing comprising:

a bioresorbable a bioresorbable graft graft layer, layer, forfor placement placement in contact in contact with with the the wound; wound;

2020269760 27 Jan a liquid impermeable a liquid occlusive impermeable occlusive outerouter layer; layer;

5 5 a fluid porous a fluid porting layer porous porting layer positioned positioned between the outer between the outer layer layer and andthe the bioresorbable graft bioresorbable graft layer; layer; andand

a a fluid fluid conduit in fluid conduit in fluid communication with communication with the the porting porting layer, layer, for coupling for coupling to a source to a source

of of negative pressure; negative pressure; 2020269760

wherein the wherein the porting porting layer layer comprises comprisesa amultiplicity multiplicity of of fluid fluid pathways betweenthe pathways between the 10 10 conduit and conduit and the the bioresorbable bioresorbable graftgraft layer; layer;

and whereinthe and wherein thebioresorbable bioresorbable graftlayer graft layercomprises comprises a plurality a plurality of of apertures apertures to to

enable fluid flow enable fluid flowfrom from the thewound to the wound to the porting porting layer, layer,each each aperture aperture comprising comprising one one or or

more slotsororslits more slots slitsthat thatdefine defineone one or or more more flaps; flaps;

whereineach wherein each flap flap is is movable movable from from a closed a closed position position in substantially in which which substantially all all of the of the 15 15 flap is flap is in in contact with the contact with thewound, wound,to to an an openopen position position to thereby to thereby increase increase the sizethe of size the of the respective aperture. respective aperture.

2. A wound 2. A wound dressing dressing as claimed as claimed in claim in claim 1, wherein 1, wherein the the bioresorbable bioresorbable graft graft layer layer

comprises a multiplicity comprises a multiplicity of of perforations perforations and/or and/or micro-channels. micro-channels.

20 20 3. A wound

3. A wound dressing dressing as claimed as claimed in claim in claim 1 or 1 or 2, 2, wherein wherein the bioresorbable the bioresorbable graft layer graft layer

comprises a plurality comprises a plurality of of mechanically mechanically interlocked interlocked bioresorbable bioresorbable graft sheets. graft sheets.

4. A A 4. wound wound dressing dressing as claimed as claimed in any in any one one of preceding of the the preceding claims, claims, wherein wherein the the 25 25 bioresorbable graft bioresorbable graft layer layer comprises comprises a first a first sheet sheet having having a plurality a plurality ofand of lugs lugs and a second a second

sheethaving sheet having a plurality a plurality of of apertures, apertures, each each lug oflug theoffirst the sheet first sheet being located being located through through a respectiveaperture a respective aperture in the in the second second sheet sheet to interlock to interlock the the first firstwith sheet sheet with the second the second

sheet. sheet.

30 5.

5.A wound 30 A wound dressing dressing as claimed as claimed in anyinone anyofone the ofpreceding the preceding claims, claims, wherein wherein the the bioresorbable graft bioresorbable graft sheets sheets comprise comprise extracellular extracellular matrixmatrix (ECM). (ECM).

6. A wound 6. A wound dressing dressing as claimed as claimed claim claim 5, wherein 5, wherein the the ECM ECM comprises comprises reticulum. reticulum.

35 35 7.

7. A wound A wound dressing dressing as claimed as claimed in any in any one ofone the of the preceding preceding claims, claims, wherein wherein each aperture each aperture

comprises two comprises two or or more more intersecting intersecting slots slots or slits, or slits, or a or a curved curved slot orslot or slit. . slit.

31

8. A wound 8. A wound dressing dressing as claimed as claimed in claim in claim 7, wherein 7, wherein the apertures the apertures are substantially are substantially X- X- shaped, Y-shaped,C-shaped, C-shaped,U-shaped, U-shaped, or or V-shaped. 27 Jan 2025 Jan 2025 shaped, Y-shaped, V-shaped.

9. A wound 9. A wound dressing dressing as claimed as claimed in any in any one one of the of the preceding preceding claims, claims, wherein wherein the the apertures apertures

55 are are formed throughthe formed through thebioresorbable bioresorbablegraft graftlayer layer by byremoving removinga a slugofofmaterial slug materialfrom from

2020269760 27 the bioresorbable the bioresorbable graft graft layer. layer.

10. 10. A Awound wound dressing dressing as as claimed claimed in in any any oneone of of thethe preceding preceding claims, claims, wherein wherein the the apertures apertures

are die cut are die cutfrom fromthe the bioresorbable bioresorbable graftgraft layer. layer. 2020269760

10 10 11.

11. A Awound wound dressing dressing as as claimed claimed in any in any one one of the of the preceding preceding claims, claims, wherein wherein the porting the porting

layer layer comprises a fluid-permeable comprises a foam. fluid-permeable foam.

12. 12. A Awound wound dressing dressing as as claimed claimed ininclaim claim11, 11,wherein whereinthe theporting porting layer layer comprises PVAfoam. comprises PVA foam. 15 15 13. 13. A Awound wound dressing dressing as as claimed claimed in any in any one one of the of the preceding preceding claims, claims, wherein wherein the porting the porting

layer is compliant layer is and compliant and porous. porous.

14. 14. A Awound wound dressing dressing as claimed as claimed in any in any one one of of preceding the the preceding claims, claims, wherein wherein an upper an upper

20 20 surface ofthe surface of theporting porting layer layer is is undulating. undulating.

15. 15. A Awound wound dressing dressing as as claimed claimed in any in any oneone of the of the preceding preceding claims, claims, further further comprising comprising a a

pressure distributionlayer pressure distribution layer between between the porting the porting layer layer and and the the occlusive occlusive layer. layer.

25 25 16.

16. A wound A wound dressing dressing as claimed as claimed in claim in claim 15, 15, the wherein wherein thedistribution pressure pressure distribution layer layer comprises comprises an an open open cellcell foamfoam or a or a three-dimensional three-dimensional fabric. fabric.

17. 17. A Awound wound dressing dressing as as claimed claimed in in claim claim 1515 or or claim claim 16, 16, wherein wherein the the pressure pressure distribution distribution

layer comprises layer comprises a plurality a plurality of of fluid fluid flow flow channels channels that that are substantially are substantially perpendicular perpendicular to to 30 30 the interface the interfacebetween betweenthe the foam foam layer layer and theand the pressure pressure distribution distribution layerfluid layer to allow to allow fluid to flow to flow through through the the pressure pressure distribution distribution layer. layer.

18. 18. A Awound wound dressing dressing as as claimed claimed in any in any one one of the of the preceding preceding claims, claims, wherein wherein the conduit the conduit

comprises comprises a a distalend distal end portion portion having having an opening an opening in fluid in fluid communication communication with the with the porting porting

35 35 layer. layer.

19. A wound 19. A wound dressing dressing as claimed as claimed in claimin18, claim 18, the wherein wherein distalthe end distal portionend portion is substantially is substantially

arch-shaped. arch-shaped.

32

20. 20. A Awound wound dressing dressing as as claimed claimed in claim in claim 18,18, wherein wherein thethe conduit conduit comprises comprises a dual a dual lumen lumen

conduit comprising a strut positioned along a central axis axis of of one oflumens the lumens to prevent 27 Jan 2025 2020269760 27 Jan 2025

conduit comprising a strut positioned along a central of one the to prevent

the conduit the conduit from collapsing under from collapsing under compression. compression.

55 21.

21. A wound A wound dressing dressing as claimed as claimed in claim in claim 20, wherein 20, wherein one lumen one lumen of theofdual the lumen dual lumen conduit conduit

is is elliptical in shape. elliptical in shape.

22. 22. A Awound wound dressing dressing as as claimed claimed in in any any oneone of of thethe preceding preceding claims, claims, wherein wherein thethe conduit conduit isis

a a dual dual lumen conduit comprising lumen conduit comprisingaaprimary primaryconduit conduittotoapply applyaanegative negativepressure pressuretotothe the 2020269760

10 10 dressing and dressing and a secondary a secondary conduit conduit for introducing for introducing fluid fluid to the to the dressing dressing or for facilitating or for facilitating

pressure measurement. pressure measurement.

23. 23. A Awound wound dressing dressing as as claimed claimed in any in any oneone of the of the preceding preceding claims, claims, wherein wherein the the dressing dressing

further comprises further comprises aasleeve sleevecomprising comprising a port a port forfor receiving receiving a portion a portion of of thethe conduit conduit

15 15 thereinin therein in aa secure securearrangement arrangement to attach to attach the conduit the conduit to the dressing. to the dressing.

24. 24. A Awound wound dressing dressing as as claimed claimed in in claim claim 23,23, wherein wherein thethe sleeve sleeve comprises comprises an elastomeric an elastomeric

material. material.

20 25.

25. 20 A wound A wound dressing dressing as claimed as claimed in claim in claim 23 or23claim or claim 24, 24, wherein wherein the the sleeve sleeve forms forms a divider a divider

between between a anegative negativepressure pressurereceiving receivingarea areaofofthe thedressing dressingand and an an ambient ambient pressure pressure

area. area.

26. 26. A Awound wound dressing dressing as as claimed claimed in in anyany oneone of of thethe preceding preceding claims, claims, wherein wherein thethe occlusive occlusive

25 25 layer comprises layer comprises a substantially a substantially transparent transparent regionregion and theand the porting porting layer comprises layer comprises one one or moreviewing or more viewingapertures apertures to to enable enable visual visual inspection inspection of least of at at least a portion a portion of the of the

bioresorbable graft bioresorbable graft layer. layer.

27. 27. A Awound wound dressing dressing as as claimed claimed in in anyany oneone of of thethe preceding preceding claims, claims, wherein wherein thethe occlusive occlusive

30 30 layer layer comprises a polyurethane comprises a sheet comprising polyurethane sheet comprisingan anadhesive adhesivesurface. surface.

28. 28. A Awound wound dressing dressing as claimed as claimed in any in any one one of the of the preceding preceding claims, claims, wherein wherein the wound the wound

dressing comprisesaamouldable dressing comprises mouldable adhesive adhesive seal seal forfor surrounding surrounding a wound, a wound, wherein wherein the the

seal comprises seal comprises butyl butyl rubber, rubber, a filler, a filler, andand a tackifying a tackifying resin. resin.

35 35 29.

29. A Awound wound dressing dressing as as claimed claimed in in claim claim 28,wherein 28, wherein the the sealisis removable seal removableand and re-sealable re-sealable

against against aapatient's patient’sskin. skin.

30. 30. A Awound wound dressing dressing as as claimed claimed in in claim claim 2828 or or claim claim 29, 29, wherein wherein the the sealisisnon-curing. seal non-curing.

33

31. 31. A Awound wound dressing as as claimed in any one one of claims 28claim to claim 30, 30, wherein the seal is is 27 Jan 2025 Jan 2025 dressing claimed in any of claims 28 to wherein the seal

removable froma askin removable from skinsurface surface by by stretching stretching the the adhered adheredseal. seal.

55 32.

32. A wound A wound treatment treatment systemsystem comprising comprising a wounda dressing wound dressing as claimed as claimed in any in oneany of one of claims claims

2020269760 27 1 1 to to 31, 31, and and aa mouldable mouldableand andremovable removable adhesive adhesive sealseal for for surrounding surrounding a wound, a wound, the the seal seal comprising butyl rubber, comprising butyl rubber, aa filler, filler, and and aa tackifying tackifying resin, resin,wherein wherein the the mouldable mouldable

adhesive sealisisapplied adhesive seal applied around around the the perimeter perimeter of the of the to wound wound to the patient’s the patient's skin. skin. 2020269760

10 33.A wound 10

33. A wound treatment treatment system system as claimed as claimed in claim in claim 32,32, wherein wherein thethe occlusivelayer occlusive layeris is adhered overthe adhered over the mouldable mouldableadhesive adhesive seal. seal.

34. 34. A Awound wound treatment treatment system system comprising comprising a wound a wound dressing dressing as claimed as claimed in any in any one one of claims of claims

1 1 to to 31, whereina anegative 31, wherein negative pressure pressure source source is coupled is coupled to theto the conduit conduit toaapply to apply a negative negative

15 15 pressure to the pressure to the wound. wound.

35. 35. AAwound woundtreatment treatmentsystem systemasasclaimed claimedininany anyone oneofofclaims claims 32 32to to 34 34and andfurther further comprising comprising a a reservoir reservoir forfor collecting collecting exudate exudate removed removed from thefrom the dressing. dressing.

34

WO wo 2020/226511 PCT/NZ2020/050044 1/26

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PCT/NZ2020/050044 3/26

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WO 2020/226511 wo 2020/226511 PCT/NZ2020/050044 11/26 11/26

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WO WO 2020/226511 2020/226511 PCT/NZ2020/050044 PCT/NZ2020/050044 13/26

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PCT/NZ2020/050044 16/26

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PCT/NZ2020/050044 18/26

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WO WO 2020/226511 2020/226511 PCT/NZ2020/050044 PCT/NZ2020/050044 19/26

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PCT/NZ2020/050044 20/26

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WO WO 2020/226511 2020/226511 PCT/NZ2020/050044 PCT/NZ2020/050044 23/26

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PCT/NZ2020/050044 25/26

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FIGURE 43